The long term objectives are to understand (i) fundamental aspects of transcription initiation, elongation, and termination mechanisms by DNA polymerases and "common" accessory factors and (ii) the overall control of gene expression (transcription) during cell growth and proliferation, cell differentiation and infection or transformation by viruses; focusing on key target genes the general objective is to elucidate the structure, mechanism of action, and regulation of key effectors (regulatory factors) of these processes, thus leading to an understanding of important intracellular signals and control points. Taking advantage of the ability to reproduce natural transcription initiation and regulatory events in reconstituted cell free systems, and the recent identification, purification and cloning of common initiation factors, regulatory factors, and a new class of cofactors, the specific aims are as follows. Relative to the first general objective, (1) to complete the cloning and expression and to provide detailed information on the structure and mechanisms of action of the numerous "common" transcription factors, (2) to determine the mechanism(s) of action of distinct classes of gene specific activators and repressors, including identification of targets in the basic transcriptional machinery and the structure and function of common or activator-specific cofactors required for these functions, (3) to investigate the role of higher order template organization, including chromatin assembly and nuclear matrix delocalization, in regulatory factor functions (induction or repression), and, ultimately, to use artificial nuclei to reconstitute a natural nuclear environment with purified genes and factors. Relative to these aims and to the second general objective, (4) to determine the mechanisms of activation of viral (adenovirus, herpesvirus, HIV, lymphotropic papovavirus) genes by both cellular factors (USF, Rel and PU.1 oncoproteins) and virus-coded factors (EIA, IE/ICP4, VP16/OTF1), (5) to investigate the regulation of cellular genes in relation to cell growth and proliferation; including elucidation of mechanisms involved in activation/repression of small structural RNA genes (5S, tRNA, snRNA), histone genes (H2B), and cellular protooncogenes (c-fos, c-myc) and determination of the functions of the products of protooncogenes (Myc) and tumor suppressor genes (Rb, P53), (6) to investigate gene regulation during B cell differentiation; including elaboration of the nature and mechanism of action of lymphoid specific factors implicated in activation of immunoglobulin genes (e.g. OCT2, BAF, NPkB, PU.1) and other stage- specific (e.g. pre B-specific) marker genes, as well as studies of the regulation of genes encoding these factors, and (7) to investigate the role of transcription (including specific factors) in DNA replication and in recombination (immunoglobulin gene rearrangements).